In recent years, a TFT that uses an oxide semiconductor for its channel layer has been receiving attention. This thin film made of an oxide semiconductor (hereinafter, also referred to as an “oxide semiconductor film”) has high mobility and high visible light transmission properties, and thus, is used for applications of liquid crystal display devices, etc. For the oxide semiconductor film, there is known, for example, an oxide semiconductor film made of InGaZnOx (hereinafter, referred to as “IGZO”) which is an oxide semiconductor using indium (In), gallium (Ga), zinc (Zn), and oxygen (O) as its main components.
Meanwhile, a liquid crystal display panel has a problem that due to entry of light into a channel layer of a TFT, changes in the threshold of the TFT occur. It is known that in a TFT using IGZO for its channel layer (which may be hereinafter referred to as an “IGZO-TFT”) in particular, the electrical conductivity level changes on the short wavelength side of visible light due to optical absorption (see, for example, Patent Document 1). Specifically, in a TFT that uses IGZO for its channel layer, changes in threshold occur due to entry of short-wavelength visible light into the channel layer. This causes a reduction in the reliability of the liquid crystal display panel.
In connection with the invention of the present application, Patent Document 2 discloses a liquid crystal display panel in which a red color filter pattern which absorbs short-wavelength light most is disposed in a position on a color filter substrate that faces a TFT on an array substrate. According to such a configuration, since short-wavelength light can be prevented from entering the channel layers of the TFTs, changes in the thresholds of the TFTs can be suppressed.